How to weld AISI 8630 Steel


Alloy Steel 8630, also known as AISI 8630, is a low alloy that is unique due to its levels of chromium, molybdenum, and chromium. Alloy Steel 8630 offers users good mechanical properties, as well as weldability by most common methods. This popular alloy works well with hot forging and rolling, in addition to annealing.

Material Specification for supply for AISI 8630

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Chemical composition of AISI 8630

  • Fe Balance
  • Mn 0.65-0.95%
  • Cr 0.4-0.6%
  • Ni 0.35-0.75%
  • C 0.28-0.33%
  • Si 0.15-0.30%
  • Mo 0.15-0.25%
  • S ≤ 0.040%
  • P ≤ 0.035%

Mechanical properties of AISI 8630

Weldability of AISI 8630

AISI 8130 is having a High Carbon Equivalent along with high strength which makes it prone to weld and HAZ cracking. Stringent control on Welding Preheat is required to avoid any weld cracking issue. Post heating after welding is very beneficial to control delayed cracking by allowing hydrogen diffusion.

After welding, the part shall be allowed to slow cool thus to prevent the formation of martensite in the weld and HAZ.

Welding electrode/ filler wire for welding AISI 8630

Welding shall be carried out using SMAW with E10018-D2 (AWS A5.5). ER100S-G shall be used when welding with TIG welding.

Preheat/ Interpass for AISI 8630

Preheat minimum of 500°F or 250°C shall be followed to prevent the formation of martensite in the weldment and HAZ. You can use our ONLINE PREHEAT CALCULATOR to find preheat temperature for any material.

If arc air gouging is the preparation method to be used, then Preheating before preparation must be exercised. Preparation for welding by re-machining or grinding does not require preheating.

Stress-relief, PWHT of AISI 8630

PWHT after welding shall be carried out at 650°C. Holding time usually based on thickness shall be 1 hour/inch. For an application requiring hardness control such as NACE requirements, holding time can be up to 4 hours to meet the 250HV limit.

Heat Treatment for AISI 8630

Annealing: For optimum machinability of this alloy, a microstructure consisting of coarse pearlite and a minimum of ferrite is considered to be optimum. Such a structure can be obtained by austenitizing at 1550°F (845°C), furnace cooling to 1350°F (730°C) then to 1180°F (640°C) at 20°F/hr. An alternative is an iso-anneal at 1225°F (660°C)

Normalizing:1600°F (870°C) and air cool.

Hardening: The alloy will be austenitized at around 1525 – 1600°F (830 – 870°C) and oil or water quenched depending upon section size and intricacy.

Tempering: To desired hardness, using temperatures based on past experience, following water or oil quench.

Machinability: This grade of alloy is readily machined following suitable heat treatment.

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